1Department of Anthropology, University of Oregon, 2Department of Anthropology, Hunter College of the City University of New York, New York Consortium in Evolutionary Primatology (NYCEP), 3PhD Program in Anthropology, Graduate Center of the City University of New York, 4Department of Anthropology, Lehman College, City University New York, NYCEP, 5Division of Paleontology, American Museum of Natural History
Thursday All day, Clinch Concourse
Taxonomy of the South African fossil colobine Cercopithecoides williamsi has been debated by paleoprimatologists for decades. It has been suggested that the cranial morphology of specimens from Makapansgat (MP), Sterkfontein (STS/SWP), and Bolt's Farm (BF) shows more variation than expected for a single species. Thirty-seven three-dimensional landmarks were collected on a target sample of six specimens of Cercopithecoides williamsi from these three sites. Additionally, a comparative sample of 287 extant and fossil colobine crania representing 17 species was also landmarked. Principal components analysis (PCA), regression, and Procrustes distances (PD) were used to compare shape differences within and among taxa to assess variation in the target sample.
Multivariate analyses show high levels of variation in the target sample, but not more than that seen in some extant species. Brow ridge thickness and brow ridge curvature have wide ranges of variation, but still fall within the ranges observed for four and three extant species respectively. BF 43 and MP 113 stand out as having relatively broad interorbital regions and increased levels of brow ridge curvature compared to other specimens in the target sample. In brow thickness, one particularly thin-browed specimen (MP3a) increases variation in the sample, while the other target specimens fall within a normal species range of variation. Based on these and the PD and PCA, we cannot reject the hypothesis of more than one species being represented in Cercopithecoides williamsi. However, the variation in cranial morphology seen in South African Cercopithecoides williamsi also appears consistent with a single species model.
This study was supported by the Wenner-Gren Foundation, the PSC-CUNY faculty research award program, NSF 0966166 (NYCEP IGERT), and the University of Oregon.